Flow regulating valve

ABSTRACT

In a chamber of a housing provided with at least one inlet and at least one outlet is accommodated a sleeve having a longitudinally extending passage as well as first and second flow ports communicating with the passage and with the inlet and outlet respectively. A throttling piston is located in the passage displaceable longitudinally thereof with reference to the first ports. A substantially fluid-flow throttling passage is provided in either the outer circumferential surface of the throttling piston or in the inner circumferential surface bounding the passage, and in any case extends longitudinally of the passage and communicates with the respective ports. A control piston is located in the passage downstream of and axially adjacent to the throttling piston for maintaining constant fluid flow through the passage.

United States Patent [1 1 [111 3,724,494 Alber [451 Apr. 3, 1973 [54]FLOW REGULATING VALVE [76] Inventor: HansAlber, 1324 Outlook Drive,Examiner-Henry Tm'mkslek Mountainside, NJ.

Assistant Examiner-Robert J. Miller Attorney-Michael S. Striker [22]Filed: Nov. 2, 1970 211 App]. No.: 86,052 [57] ABSTRACT In a chamber ofa housing provided with at least one inlet and at least one outlet isaccommodated a sleeve [30] Application Pnomy having a longitudinallyextending passage as well as Nov. 3, 1969 Germany ..P 19 55 044.3 firstand Second flow Ports communicating with the passage and with the inletand outlet respectively. A [52] US. Cl ..137/501 throttling Piston islocated in the passage displaceable 51 Int. Cl. ..csu 7/00 mgimdinallythem with reference first 58 Field of Search ..137/o1,so4,s03; 138/44,sb,stal?tiany thmmingPassage is 138/42 vlded in either the outercircumferential surface of the throttling piston or in the innercircumferential surface bounding the passage, and in any case extends[56} Reerences Cited longitudinally of the passage and communicates withUNITED STATES PATENTS the respective ports. A control piston is locatedin the passage downstream of and axially adjacent to the 2,570,351 /1951KlCSSlg ..l37/501X throttling piston for maintaining constant fluid flow3,402,735 9/1968 Kates ..137/s01 through the passage 3,554,221 1/1971McMurry et a]. ..l37/5Ol 3,554,222 1/1971 Kihara et al. ..l37/S01 22Claims, 4 Drawing Figures 50' 16 1a 61. a1 63 44 +0 60 5b 93 76 27 32 9D1 17 14 18 4 as I v inilililil/////I/l////i)/ i1 l a {it 7/ 700 2| P t rEL. '11 1115' i i :1 a 1 P,

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IN VENTOR (um M392 ATTORNEY FLOW REGULATING VALVE BACKGROUND OF THEINVENTION The present invention relates generally to a valve, and moreparticularly to a regulating valve. Still more particularly theinvention relates to a flow regulating valve for liquids and gases, andespecially for liquids v and gases which flow in small quantities.

Such regulating valves are basically already well known. Generallyspeaking they are provided with a throttling aperture thecross-sectional area of whichthrough which the fluid flows-can be variedto thereby vary the quantity of fluid which flows through per unit oftime. The known constructions are all more or less serviceable, but ithas been found that if the quantity of fluid passing through the valveis lower than approximately 30 cm /min, the known valves of this type nolonger assure reliable and certain regulating of the flow quantity. Thereason for this is that throttling apertures having a diameter ofapproximately 0.4 mm and less have a tendency to become clogged after arelatively brief period of time, even if the fluid being passes throughthe valve is well filtered. It is not yet entirely clear, in fact, whythis should be the case'despite proper precautions taken to assure goodfiltration, but the fact remains that this is what happens. For thisreason the known constructions are not satisfactory where smallquantities of flowing fluid are to be regulated.

SUMMARY OF THE INVENTION It is, accordingly, an object of the presentinvention to overcome the aforementioned disadvantages.

MOre particularly it is an object of the present invention to provide animproved fluid flow regulating valve which permits reliable and accurateregulation of even small and very small quantities of fluid flowingthrough the valve.

An additional object of the invention is to provide such a valve whichis comparatively simple in its construction.

A concomitant object of the invention is to provide such a valve whichis not subject to clogging and similar malfunctions during operation.

In pursuance of the above objects, and others which will become apparenthereafter, one feature of the invention resides, briefly stated, in aflow regulating valve for fluids which comprises a housing having achamber provided with at least one inlet and at least one outlet. Asleeve is accommodated in the chamber and has a longitudinally extendingpassage bounded by an inner peripheral surface and first and second flowports com-- municating with the passage and with the inlet and outlet,respectively, and which flow ports are at least in part bounded byflow-controlling edge portions. A throttling piston is accommodated inthe passage displaceable longitudinally thereof with reference to thefirst ports and to the edges bounding the same and has an outerperipheral surface. A substantially helical fluid-flow throttlingpassage is provided in and extends longitudinally of one of the surfacesand a control piston is accommodated in the passage downstream of andaxially adjacent to the throttling piston for maintaining the flow offluid through the throttling passage constant.

The provision of the throttling passage in helically convoluted form, orin a form approaching helical convolutions such as an essentially spiralconfiguration, makes it possible to regulate and control reliably andconstantly quantities of flowing fluid as low as 0.1 cm lmin and evenlower. Such regulation is independent of the pressure prevailing at theinlet and the outlet of the valve. The tolerance of the through-putquantity, that is the quantity of fluid which flows per unit of timethrough the valve, is approximately :1 percent of the predeterminedthrough-put value, that is the value which has been previously set with.the valve.

The valve according to the present invention has a wide range ofapplicability. It is particularly suitable for controlling the flow ofhydraulic oils, especially those having a viscosity range ofapproximately 1 to approximately 3 cSt (centistoke) and for pressures upto approximately 300-350 kp (kilopound) per cm. It is emphasized,however, that the valve is well suited for regulating the flow of othermedia, also, that is for liquids as well as for gases. The valveaccording to the present invention may be a two-way valve ora threewayvalve and may be actuated-for displacing of the throttling piston in asense varying the through-put quantityin mechanical, hydraulic,pneumatic or electric manner. y

- While it has been indicated before that the throttling passage may beprovided either in the outer peripheral surface of the throttling pistonor in the inner peripheral surface bounding the passage of the sleeve inwhich the piston is accommodated, it is particularly advantageous toprovide the throttling passage in the outer peripheral surface of thethrottling piston itself. In this case it is preferred to provide anannular groove at the upstream end and the downstream end of thepassage, also in the outer peripheral surface of the throttling piston.The throttling passage may have-but need not have-a cross-sectional areaof approximately 0.2 mm and a length of 15 cm. Naturally this is only byway of example and can be varied in dependence upon particularrequirements. If the cross-sectional area is approximately 0.2 mm, thiscorresponds to a conventional throttling aperture of the prior arthaving a diameter of approximately 0.5 .mm. It has been found becomeclogged if the fluid is previously filtered, and

accordingly the helical throttling passage according to the presentinvention also does not become clogged, being the equivalent of aconventional throttling passage of the aforementioned diameter, butpermitting the control of small fluid-flow quantities which a throttlingpassage of the conventional type and having the aforementioned diameterwould not permit.

ltis advantageous thatthe pitch between the convolutions of thethrottling passage be greater than is the width of the throttlingpassage in the region of the outer circumferential or peripheral surfaceof the throttling piston. If so constructed, the ribs located betweenthe individual convolutions have at the outer peripheral surface of thethrottling piston cylindrical surfaces which are of course annularsurface portions of the outer peripheral surfaces of the piston. This,in turn, makes possible a precise guidance of the throttling piston inthe sleeve and prevents the liquid streaming through the throttlingpassage from skipping axially of the throttling passage by leakingoutside the passage between the outer circumferential surface of thepiston and the inner circumferential surface of the passage in thesleeve.

It is advantageous to locate a separate throttling aperture downstreamof the spiral throttle which is constituted by the provision of theaforementioned throttling passage. This separate or additionalthrottling passage is also provided on the throttling piston and byhaving the helical throttling passage and the additional throttlingpassage or throttling aperture in communication with one another, acombination is obtained in which fluid throughput quantities ofapproximately 0.1 to approximately 40 em /min through the spiralthrottle can be precisely and constantly regulated. These smallquantities of fluid pass through the throttling aperture without beinginfluenced thereby but quantities in excess of approximately 40 cm perminute are regulated and controlled through the throttling aperture. ifsuch quantities occur, that is if 40 cm /min are exceeded, they remainuninfluenced by the spiral throttle.

If a separate throttling aperture of the type discussed above isprovided, then it is advantageous to configurate it in form of atriangular recess in the outer peripheral surface of the throttlingpiston, extending axially of the latter and having one corner whichmerges into and communicates with an axially extending groove connectingit with the outlet of the helically convoluted throttling passage. Morespecifically, this groove preferably communicates with the annulargroove provided in the throttling piston at the downstream end of thehelical throttling passage and the cross-sectional area of the axiallyextending groove should preferably be the same or larger than thecrosssectional area of the helical throttling passage itself.

It will be appreciated that precise regulating of the through-put in theregion of the spiral throttle constituted by the helical throttlingpassage, can be obtained and reproduced because of the considerablelength of the helical throttling passage which, as pointed out before,may be on the order of cm. This is a feature which cannot be obtainedwith throttling apertures in the prior-art constructions because thesmall adjustments required in varying the cross-sectional area of suchconventional throttling apertures make it impossible to provide preciseadjustments for very small throughput quantities. Where throttlingapertures are used, throughput quantities of 30 cmlmin and greater arecontrollable reliably and with only small dependency on the viscosity ofthe fluid itself. In spiral throttles, such as the one constituted bythe helical throttling passage provided in accordance with the presentinvention, throughputs in excess of 40 em /min are more stronglydependent on the viscosity of the fluid. The low flow speed of thefluid, for instance oil, in conduits at throughput quantities up to 40em /min a complete temperature equalization between the oil and theambient temperature takes place. Because the ambient temperature isalmost constant in air-conditioned spaces, temperature variations suchas they occur in the oil storage containers of hydraulic systems, haveno influence on the constancy of regulation of throughput in spiralthrottles. However, where throughput exceeds 40 cm /min, the greaterflow speed of the fluid, such as oil, makes it impossible to obtain thistemperature equalization without considerable difficulties and for thisreason the throttling aperture provided according to the presentinvention and located downstream of the spiral throttle acts at flowspeeds in excess of 40 em /min, and provides control, this being clearlyadvantageous because its throughput quantity is independent of theviscosity of the flowing fluid. It is clear, therefore, that byconstructing the valve as just pointed out, as a combination throttle,small and very small throughput quantities can be regulated through thespiral throttle component, and larger and large throughput quantities upto any specified desired size can be reliably and constantly regulatedthrough the throttling aperture component, and in the latter case ofcourse there is no danger that the throttling aperture could becomeclogged, just as there is no danger that the spiral or helicalthrottling passage could become clogged at the lower through-putquantities.

According to a further concept of the invention which is highlyadvantageous, it is advisable to mount and guide the regulating orcontrol piston of the valve according to the present invention inantifriction bearings, e.g., ball bearings, because especially ifprecision-manufactured bearing balls are utilized, the control piston iscentrally guided in the passage of the sleeve. This assures uniformradial play between the circumference of the control piston and theinner surface bounding the passage of the sleeve, and substantiallyreduces leakage losses as compared to the previously utilized controlpistons. For instance, by resorting to this concept of the presentinvention the leakage of oil due to play between the control piston andthe inner surface bounding the passage of the sleeve is reduced due tothe concentric position of the control piston in the passage by a factorof approximately 2.5 as compared to what is experienced when the controlpiston is located in the passage in eccentric relationship. Thus, thecontrol piston according to the present invention has a fluid leakagewhich is approximately 250 percent smaller than that of correspondingcontrol pistons known from the art.

Furthermore, the very low friction obtained in this manner between thecontrol piston and the sleeve in which it is accommodated, reduces orentirely eliminates disadvantageous influences upon the operationalaccuracy of the valve. In the prior art, where the control pistons wereslidably mounted rather than by means of antifriction bearings, thefunctional accuracy of such valves was substantially limited anddisadvantageously influenced, particularly at higher pressures, due tostatic and dynamic friction. Of course it will be appreciated that as aresult of the reduced very low friction experienced by mounting thecontrol piston according to the present invention on antifrictionbearings, lower regulating forces are obtained with the result that thecross-sectional area of the throttling channel, the spiral throttle andthe cross-section of the throttling aperture can be made larger thanwould otherwise be possible, thereby reducing the danger of cloggingstill further. In addition, the easy movement of the regulating orcontrol piston guarantees a constancy of the once-set throughputquantity within a tolerance of approximately :1 percent, an advantagewhich was pressed against the inner surface bounding the sleeve,

passage by the fluid under pressure.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

.BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial section through acurrently preferred embodiment of my invention;

FIG. 2 is a sectional detail view, on an enlarged scale, showing adetail of thethrottling piston of the valve in FIG. 1;

FIG. 3 is a side view of the throttling piston shown in FIG. 2; and I vFIG. 4 is a fragmentary enlarged detail view of FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS- Discussing now the embodimentillustrated in FIGS. 1-4 it will be seen that reference numeral 1identities in toto a flow regulating valve according to my presentinvention. The valve comprises a housing 12 which in the illustratedembodiment has its interior chamberclosed at opposite axial ends' by endcaps or end walls 14 and 16 which may be secured to the housing 12 bymeans of screws or in other suitable manner'which is not a part of thepresent invention. It will also be'understood that ordinarily suitableseals, which are not separately shown, suchas O-rings or the like, areused to seal the juncture between the end walls and the housing 12 toprevent an escape of the fluid flowing through the valve. l

Accommodated in the chamber of the housing 12 extending axiall thereofis a control sleeve or sleeve 20 whose length corresponds substantiallyto that of the housing 12. Again, suitable seals are not illustrated butwill be provided between housing and sleeve and this is a conventionalexpedient and need not therefore be further discussed. One end of thesleeve 20 may abut against the end wall 16 whereas the other end of thesleeve may be subjected to a biasing force, for instance by means of. adished spring 22 which abuts against the end wall 14 so that the sleeve20 is constantly biased against the end-wall 16.

As FIG. 1 also shows, at least one inlet 24 is provided in the housing12 for admission of the fluide.g., oilwhose flow is to be controlled.After entering the inlet '24 the fluid advances'into an annular. channel28 provided in the housing 12 and passes through the valve to finallyexit through the exit or outlet 26 of which at least one is provided(see the broken-line showing in FIG. 1). The pressure P, prevails in theinlet 24 whereas a different pressure p prevails in the outlet 26 aswill be discussed further below. Oncehaving entered the annular channel28, the fluid flows through one or more radially or substantially radialbores 30 in the sleeve 20 to the interior of the latter to enter anannular channel 32 provided for this purpose within the sleeve 20. FIG.1 further shows that the sleeve 20 is also provided with an axialpassage or bore 21 extending over its entire length and accommodating athrottling piston 40 in the left-hand side of FIG. 1.

The throttling piston 40 is shown in FIG. 1, and details are mostreadily visible from FIGS. 2, 3 and 4 where it will be seen that it hasa cylindrical portion 2 which is followed in downstream directionthat istowards the right-hand side in FIG. 1-by an annular channel 44 providedin this instance by the outer peripheral surface of the piston 40. Theannular channel 44 is located in a plane normal to the longitudinal axisof the piston 40 and is followed by and in communication with ahelically convoluted throttling passage 46 provided also in the outerperipheral surface of the piston 40 and extending axially of the latter.At the downstream end of the passage 46 there is provided incommunication with it an additional annular channel 48 which is alsolocated in a plane normal to the longitudinal axis of the piston 40.Downstream of the channel or groove 48 there is provided afurther-cylindrical portion 49 of the throttling piston 40, as forinstance shown in FIG. 3. Itis to be mentioned aperture 52 which isclearly visible in FIGS. Mind 3 in particular, and which in theillustrated embodiment is in form of a triangularly configur'atedrecess, a corner 53 of which (compare FIG. 3) communicates with theannular channel 48 via a groove'50"provided inthe outer surface of thepiston 40 and extending axiallythereof.

Reference to FIG. 1 willshow that the right-hand end (in FIG. 1) of thepiston 40 abuts against an annular insert 54 which in turn is heldagainst displacement towards the right in FIG, 1 by a retaining ring 56,for irlstance a circlip, which hasa spring characteristic and in partprojects into a recess provided for. this purpose whereas in'part itabuts against the insert 54. The piston 40 is. hollow, beingprovidedwith an axial .bore 58 which begins atan inner bottom wall 63(see the lefthand side in FIG. 1) and which at the right-hand endportion (that is the downstream end portion) of the piston 40 mergesinto a conically diverging bore portion 60 (compare FIG. 2).

As already pointed out earlier, the piston 40 can be displaced axiallyin the passage of the sleeve 20. FIG. 1 shows that an expansion spring62, for instance a helical spring, is accommodated between the insert 54and the end face 63, permanently tending to displace the piston 40towards the left-hand side in FIG. 1 so that its outer end face 61 abutsagainst a pin 64. In a manner which is not illustrated in detail butwhich will be obvious to those skilled in the art the pin 64 can beaxially displaced as indicated by the double-headed arrow associatedwith it, via a setting member 66 which is threaded onto a projection 67of the end wall 16 and acts via an intermediate element 68 upon the pin64.

The means which has been diagrammatically illustrated in FIG. 1indicates that displacement of the pin 64 can be effected in mechanicalmanner, in hydraulic manner, in pneumatic manner or in electric manner,all means of this type being well known to those skilled in the art andtherefore requiring no specific discussion. The spring 62 urges thepiston 40 against the inner end portion of the pin 64 so that turning ofthe member 66 and a resulting axial displacement of the pin 64 willnecessarily result in a concomitant axial shifting of the throttlingpiston 40 within and relative to the sleeve 20. An axial bore providedin the portion 42 of the throttling piston 40 connects the bore 58 withthe space 71 in the sleeve to provide for a pressure equalization whenmovement is to be effected.

The cross-sectional configuration of the helical throttling passage 46may be selected within a considerable range of possibilities. It may begenerally polygonal, it may be quadratic, it may be rectangular, it maybe at least substantially semi-circular or, as illustrated in theembodiment here described and as shown in FIG. 4 in particular, it maybe triangular. In the illustrated embodiment the width of the passage46in the region of the outer periphery of the throttling piston 40 issmaller than the pitch between the convolutions of the helicalthrottling passage 46, so that ribs 34 remain between the individualturns 33 of the passage 46, which each have a cylindrical outercircumferential surface 35. It is preferable but not necessary that thecross-sectional configuration of the groove 50 be the same as that ofthe helical throttling passage 46, and preferably the cross-sectionalarea of the groove 50 should also be the same as that of the throttlingpassage 46. It is emphasizedthat the cross-sectional passage of thegroove 50 may also be larger than that of the throttling passage 46, butthat it should be no smaller for obvious reasons.

FIG. 1 shows that there is accommodated in the sleeve 20 in downstreamdirection from the circlip 56 a tubular portion 72 having a bore 74 andabutting with its upstream end against the circlip 56. Also locateddownstream of the piston 40 and in alignment therewith there isaccommodated in the sleeve 20 a control or regulating piston 80 which issimilarly axially displaceable within and with reference to the sleeve20. FIG. 1 shows that it is provided with a blind bore 82 with whichthere communicates at least one radial bore 84 which in turncommunicates with an annular channel 86 provided in the outer peripheryof the control piston 80.

A control edge 88 on the annular channel 86 is located in theillustrated embodiment in a plane normal to the longitudinal axis of thecontrol piston 80 but could also be located in a plane which is inclinedto the longitudinal axis. It cooperates with radially extending controlbores 90 provided in the sleeve 20 which in turn communicate with anannular channel 92 in the housing 12 an enlarged portion 93 of whichchannel communicates with the outlet 26. It is clearly shown in FIG. 1that the control bores in the sleeve 20 are offset with reference to oneanother in axial direction of the sleeve 20.

A spring 76, such as a helical spring or the like, is ac commodatedbetween the end 81 of the control piston 80 and the tubular portion 72,continuously urging the control piston 80 towards the right in FIG. 1,that is in downstream direction as seen with reference to the flow offluid through the valve. The rear or downstream end 83 of the controlpiston 80 communicates with the inlet 24 and the incoming fluid thereinvia a conduit 94 and/or a direct connection 96, an annular space 98 andat least one radially oriented passage 100. This means, in other words,that the unthrottled inlet pressure P,- which prevails in the inlet24-also acts upon the rear or downstream end 83 of the control piston80. If desired, a damping or regulating screw 102 may be positioned inthe conduit 94 as shown.

It has already been pointed out earlier that according to a preferredembodiment of the invention the control piston 80 is mounted in thesleeve by means of antifriction bearings. FIG. 1 shows that it isprovided for this purpose at its two axial ends with respectivecylindrical projections and 112. A bearing cage 114 surrounds theprojection 110 and a similar cage 116 surrounds the projection 112 andboth are provided with axially extending slots and 117, respectively, inwhich bearing balls 118 and 120 are accommodated, respectively.Preferably but not necessarily the bearing balls 1 18 and 120 will beprecision-manufactured steel balls which roll directly upon thecylindrical outer surfaces of the projections 110 and 112 on the onehand, and on the cylindrical inner surface bounding the passage of thesleeve 20, thereby assuring an extraordinarily precise journalling andguidance of the control piston 80 in the sleeve 20. This eliminatesall'danger that the regulating or control piston 80 could becomeinclined or skew with reference to the axis of the passage of the sleeve20, causing difficulties in its axial displacement and in the executionof its control functions. Retaining rings 122, such as circlips or thelike, retain the cages 114 and 1 16 against axial displacement.

In operation of my novel regulating valve as illustrated in theaforedescribed exemplary embodiment, liquid-cg, oil-enters the inlet 24,being for instance supplied by a non-illustrated pump. From the inlet 24it passes into the annular channel 28, from the there through the bores30 and the annular channel 32 into the annular channel 44 of the piston40. At this time the oil still has the inlet pressure P and FIG. 1 showsthe throttling piston 40 in the position in which the throughput perunit of time is the smallest. In other words, from this position thepiston 40 can bedisplaced to increase the throughput per unit of time.

The oil passes from the annular channel 44 into the first turn 33 of thehelically convoluted throttling passage 46, and then proceeds totraverse the entire length of the throttling passage 46 to exit into theannular channel 48 from where it passes via the groove 50 and thethrottling aperture 52 into the space 55. In this space there exists anintermediate pressure P In dependence upon turning of the element 66 anda consequent axial displacement of the pin 64, the throttling piston 4can be displaced towards the left in FIG. 1

from the illustrated position to thereby increase the 1 throughput perunit of time to a desired value. A control edge 130 provided on thesleeve 20 and located in a plane normal to the longitudinal axis of thesleeve, controls the flow of liquid or gas into the throttling passage46. It will be appreciated that depending upon the axial position of thethrottling piston 40-as selected by axial displacement of the pin 64-aportion of the throttling passage 46 of greater or lesser length will becovered by the inner wall of the sleeve 20 or will be uncovered thereby,depending upon how far the piston 40 is'moved towards the left in FIG. 1so that a requisite portion of the throttling passage 46 has moved pastthe control edge 130. Evidently, incoming fluid need not pass throughthat length of the helical throttling passage 46 which in FIG. 1 islocated towards the left of the control edge 130. It follows from thisthat an exceedingly precise setting and control of the throughputquantity can be obtained. Moreover, the pitch and the length of thethrottling passage 46 can be freely selected according to particularrequirements encountered in actual use.

It will be appreciated that depending upon the position of thethrottllng piston 40 within the sleeve 20, the

fluid must flow either through the entire length of the I throttlingpassage 46 (as is the case in the position illustrated in FIG. 1) oronly through a portion of the length of the throttling passage 46. Inevery case, however, the fluid will also flow through the throttlingaperture 52. In fact, it is possible bydisplacing the throttling piston40 all the way to the left in FIG. 1, to have the fluid flow onlythrough the throttling aperture 52 and not at all through any portion ofthe throttling passage 46.

When the fluid arrives in the space 55 it is at an intermediate pressurePZ which acts upon the end 81 of the control piston 80, together withthe force of the spring 76. It will be appreciated that when it is saidthat the force acts upon the end 81 the entire cross-sectional areaexposed to this force is meant. The regulating piston or control piston80 will be in a position of equilibrium only when the force T actingupon its opposite or downstream end 83 (again the entire crosssectionalarea at this end 83 is meant) is equal to the sum of the forces whichact upon its upstream end 81. In other words, the force P1 must equalthe force of the springs 76 and the intermediate force PZ. Thisequilibrium is obtained and maintained by the control edge 88 of theregulating piston or control piston 80. This control edge 88 covers,depending on the axial position of the piston 80, a larger or smallerportion of the area of the control bores 90 and thus provides for thedesired constant pressure drop at the throttling piston 40. The fluidpasses from the control bores 90 into the annular channel 92 and fromthere via the outlet 26 to the user device.

Due to the continuous control operation exerted by the control piston80, the pressure drop P :PZ remains constant, independently of the valueof the pressure at the inlet 24 and the-outlet 26. This means that theonce-selected throughput quantity of the valve also remains constant.However, it should be kept in mind that the inlet pressure P should belarger by at least approximately 2 kp/cm' than the outlet or workingpressure P,

The throughput quantity per unit of time depends on the length of thethrottling passage 46 through which the fluid must flow, or upon theselected throughput cross-section of the throttling aperture. Thisquantity can be determined in accordance with the following formula:

Q throughput quantity per unit of time d hydraulic diameter of thecross-section of the helical throttling passage v viscosity of the fluidflowing through the valve 1 =length of that portion of the throttlingpassage through which the fluid flows p= pressure drop at the spiralthrottle c a constant.

The throughput quantity for the throttling aperture 52 is determined bythe following formula:

wherein Q throughput quantity per unit of time a a throughputcoefficient E flow-through-aperture cross-section g gravity accelerationAp pressure drop at the throttling aperture y specific weight of theflowing fluid If the inlet pressure P is subject to fluctuations, thenthe control piston whose surface does not contact the inner surface ofthe sleeve 20 because of its mounting in the ball bearings is capable offollowing with great precision such pressure fluctuations. Furthermore,because due to the uniform radial play and the small friction betweensleeve 20 and control piston 80 a clamping and retention of the latterin the sleeve 20 is impossible, the control bores were capable of beingdisplaced or offset with reference to one another axially of the sleeve20, so that for instance at the smallest throughput quantities one ofthe two bores 90 is completely covered by the control edge 88 of thecontrol piston 80 and is thereby closed, so that the fluid can streamoutwardly to the outlet 26 only through the remaining control bore 90.This arrangement of the control bores 90 substantially reduces theuncontrollable leakage of fluid over what is known from the conventionalvalves of this type where the control piston is not mounted inantifriction bearings and where the control bores are located in a planenormal to the longitudinal axis of the control piston; in order toprevent hydraulic clamping or seizing of the control piston,particularly at higher pressures.

As already pointed out before, due to the low-friction automaticadjustment of the control piston 80 in dependence upon pressurefluctuations, the oncedetermined or set throughput quantity can bemaintained within a tolerance of approximately i1 percent with referenceto the preset quantity, and this can be maintained constant at alltimes. Furthermore, a rapid and precise setting of the desiredthroughput quantity per time unit is made possible due to the fact thatthe throttling piston 40 is in constant abutment with and thus followswithout play precisely any axial displacements of the pin 64, due to thespring acting upon it and urging it against the pin 64.

Because the throughput quantity through the spiral throttle in theembodiment illustrated in the drawing depends on the length of thehelical throttling passage 46, it is possible to correspondinglyincrease the crosssectional area of the throttling passage 46 as thethrott ling passage is made longer, thereby further reducing thepossibility that the throttling passage might become clogged.

A non-illustrated flange or similar means is provided via which thevalve is connected to the conduit system with which it is to beassociated, with suitable seals of course again being provided.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in aflow regulating valve, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, theforegoing will so fully reveal the gist ofthe present invention that others can be applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A flow regulating valve for fluids, comprising a housing having achamber provided with at least one inlet and at least one outlet; asleeve accommodated in said chamber and having a longitudinallyextending passage bounded by an inner peripheral surface and first andsecond flow ports communicating with said passage and with said inletand outlet, respectively, and which are at least in part bounded byflow-controlling edge portions; a throttling piston in said passagedisplaceable longitudinally thereof with reference to said first portsand to the edges bounding the same, said throttling piston having anouter peripheral surface; a

substantially helical fluid-flow throttling passage proing a pair ofannular grooves in said outer peripheral surface at the upstream anddownstream ends of said throttling passage, respectively, andcommunicating with the latter.

5..A valve as defined in claim 2, said throttling passage being ofpolygonal cross-sectional configuration.

6. A valve as defined in claim 5, wherein said throttling passage is oftriangular cross-sectional configuration.

7. A valve as defined in claim 5, wherein said throttling passage is ofsubstantially quadratic cross-sectional configuration.

8. A valve as defined in claim 2, said throttling passage being of atleast substantially semicircular cross-sectional configuration.

9. A valve as defined in claim 2, wherein the crosssectional area ofsaid throttling passage is on the order of 0.2 mm.

10. A valve as defined in claim 2, said throttling piston having anouter diameter of substantially 12 mm, and said throttling passagehaving a length of substantially 15 cm.

11. A valve as defined in claim 3, said helical throttling passagehaving a pitch which is greater than its width in the region of saidouter surface so as to form between the turns of said helical throttlingpassage ribs which are bounded by cylindrical sections of said outersurface. 12. A valve as defined in claim 2, said throttling passageconstituting a spiral throttle; and further comprising a throttlingaperture provided in said throttling piston downstream of andcommunicating with said throttling passage. l

13. A valve as defined in claim 12', further comprising acircumferential groove in the outer periphery of the throttling pistonand connecting said throttling passage and throttling aperture forcommunication of the same with one another.

14. A valve as defined in claim 13, said throttling passage and a firstportion of said throttling aperture having at least substantiallyidentical cross-sectional areas. I

15. A valve as defined in claim 13, said throttling aperture including asecond portion configurated as an axially extending triangular recessprovided in said peripheral surface of said throttling piston and havinga corner facing upstream and communicating with said groove.

16. A valve as defined in claim 1, wherein said one surface is saidinner peripheral surface. I

17. A valve as defined in claim 1; and further comprising antifrictionbearing means journalling and guiding said control piston for movementthereof axially of said passage.

18. A valve as defined in claim 17, said bearing means comprising ballbearings.

19. A valve as definedin claim 1; and further comprisingmechanical'displacing means for axially displacing said throttlingpiston in said passage.

20. A valve as defined in claim 1; and further comprising electricaldisplacing means for axially displacing said throttling piston in saidpassage.

21. A valve as defined in claim 1; and further comprising hydraulicdisplacing means for axially displacing said throttling piston in saidpassage.

22. A valve as defined in claim 1; and further comprising pneumaticdisplacing means for axially displacing said throttling piston in saidpassage.

1. A flow regulating valve for fluids, comprising a housing having achamber provided with at least one inlet and at least one outlet; asleeve accommodated in said chamber and having a longitudinallyextending passage bounded by an inner peripheral surface and first andsecond flow ports communicating with said passage and with said inletand outlet, respectively, and which are at least in part bounded byflow-controlling edge portions; a throttling piston in said passagedisplaceable longitudinally thereof with reference to said first portsand to the edges bounding the same, said throttling piston having anouter peripheral surface; a substantially helical fluid-flow throttlingpassage provided on an extending longitudinally of one of said surfaces;and a control piston in said passage downstream of and axially adjacentto said throttling piston for maintaining constant the flow of fluidthrough said passage.
 2. A flow regulating valve as defined in claim 1,wherein said one surface is said outer peripheral surface of saidthrottling portion.
 3. A valve as defined in claim 2, wherein saidthrottling passage is provided in said outer surface.
 4. A valve asdefined in claim 2; and further comprising a pair of annular grooves insaid outer peripheral surface at the upstream and downstream ends ofsaid throttling passage, respectively, and communicating with thelatter.
 5. A valve as defined in claim 2, said throttling passage beingof polygonal cross-sectional configuration.
 6. A valve as defined inclaim 5, wherein said throttling passage is of triangularcross-sectional configuration.
 7. A valve as defined in claim 5, whereinsaid throttling passage is of substantially quadratic cross-sectionalconfiguration.
 8. A valve as defined in claim 2, said throttling passagebeing of at least substantially semicircular cross-sectionalconfiguration.
 9. A valve as defined in claim 2, wherein thecross-sectional area of said throttling passage is on the order of 0.2mm2.
 10. A valve as defined in claim 2, said throttling piston having anouter diameter of substantially 12 mm, and said throttling passagehaving a length of substantially 15 cm.
 11. A valve as defined in claim3, said helical throttling passage having a pitch which is greater thanits width in the region of said outer surface so as to form between theturns of said helical throttling passage ribs which are bounded bycylindrical sections of said outer surface.
 12. A valve as defined inclaim 2, said throttling passage constituting a spiral throttle; andfurther comprising a throttling aperture provided in said throttlingpiston downstream of and communicating with said throttling passage. 13.A valve as defined in claim 12; further comprising a circumferentialgroove in the outer periphery of the throttling piston and cOnnectingsaid throttling passage and throttling aperture for communication of thesame with one another.
 14. A valve as defined in claim 13, saidthrottling passage and a first portion of said throttling aperturehaving at least substantially identical cross-sectional areas.
 15. Avalve as defined in claim 13, said throttling aperture including asecond portion configurated as an axially extending triangular recessprovided in said peripheral surface of said throttling piston and havinga corner facing upstream and communicating with said groove.
 16. A valveas defined in claim 1, wherein said one surface is said inner peripheralsurface.
 17. A valve as defined in claim 1; and further comprisingantifriction bearing means journalling and guiding said control pistonfor movement thereof axially of said passage.
 18. A valve as defined inclaim 17, said bearing means comprising ball bearings.
 19. A valve asdefined in claim 1; and further comprising mechanical displacing meansfor axially displacing said throttling piston in said passage.
 20. Avalve as defined in claim 1; and further comprising electricaldisplacing means for axially displacing said throttling piston in saidpassage.
 21. A valve as defined in claim 1; and further comprisinghydraulic displacing means for axially displacing said throttling pistonin said passage.
 22. A valve as defined in claim 1; and furthercomprising pneumatic displacing means for axially displacing saidthrottling piston in said passage.